// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/quic/crypto/null_encrypter.h"

#include "net/quic/quic_data_writer.h"
#include "net/quic/quic_utils.h"

using base::StringPiece;
using std::string;

namespace net {

const size_t kHashSizeShort = 12; // size of uint128 serialized short

NullEncrypter::NullEncrypter() { }

bool NullEncrypter::SetKey(StringPiece key)
{
    return key.empty();
}

bool NullEncrypter::SetNoncePrefix(StringPiece nonce_prefix)
{
    return nonce_prefix.empty();
}

bool NullEncrypter::EncryptPacket(QuicPathId /*path_id*/,
    QuicPacketNumber /*packet_number*/,
    StringPiece associated_data,
    StringPiece plaintext,
    char* output,
    size_t* output_length,
    size_t max_output_length)
{
    const size_t len = plaintext.size() + GetHashLength();
    if (max_output_length < len) {
        return false;
    }
    uint128 hash = QuicUtils::FNV1a_128_Hash_Two(
        associated_data.data(), associated_data.size(), plaintext.data(),
        plaintext.size());
    // TODO(ianswett): memmove required for in place encryption.  Placing the
    // hash at the end would allow use of memcpy, doing nothing for in place.
    memmove(output + GetHashLength(), plaintext.data(), plaintext.length());
    QuicUtils::SerializeUint128Short(hash,
        reinterpret_cast<unsigned char*>(output));
    *output_length = len;
    return true;
}

size_t NullEncrypter::GetKeySize() const
{
    return 0;
}

size_t NullEncrypter::GetNoncePrefixSize() const
{
    return 0;
}

size_t NullEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const
{
    return ciphertext_size - GetHashLength();
}

size_t NullEncrypter::GetCiphertextSize(size_t plaintext_size) const
{
    return plaintext_size + GetHashLength();
}

StringPiece NullEncrypter::GetKey() const
{
    return StringPiece();
}

StringPiece NullEncrypter::GetNoncePrefix() const
{
    return StringPiece();
}

size_t NullEncrypter::GetHashLength() const
{
    return kHashSizeShort;
}

} // namespace net
